[COMMITTED 2.32] Remove __warn_memset_zero_len [BZ #25399]

[COMMITTED 2.32] Remove __warn_memset_zero_len [BZ #25399]

[Siddhesh Poyarekar]

Non-gcc compilers (clang and possibly other compilers that do not
masquerade as gcc 5.0 or later) are unable to use
__warn_memset_zero_len since the symbol is no longer available on
glibc built with gcc 5.0 or later.  While it was likely an oversight
that caused this omission, the fact that it wasn't noticed until
recently (when clang closed the gap on _FORTIFY_SUPPORT) that the
symbol was missing.

Given that both gcc and clang are capable of doing this check in the
compiler, drop all remaining signs of __warn_memset_zero_len from
glibc so that no more objects are built with this symbol in future.

(cherry-picked from dc274b141666766b8ef70992d887e3c0c5e41bed)
---
 string/bits/string_fortified.h | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/string/bits/string_fortified.h b/string/bits/string_fortified.h
index 309d0f39b2..c8d3051af8 100644
--- a/string/bits/string_fortified.h
+++ b/string/bits/string_fortified.h
@@ -22,11 +22,6 @@
 # error "Never use <bits/string_fortified.h> directly; include <string.h> instead."
 #endif
 
-#if !__GNUC_PREREQ (5,0)
-__warndecl (__warn_memset_zero_len,
-	    "memset used with constant zero length parameter; this could be due to transposed parameters");
-#endif
-
 __fortify_function void *
 __NTH (memcpy (void *__restrict __dest, const void *__restrict __src,
 	       size_t __len))
@@ -58,16 +53,6 @@ __NTH (mempcpy (void *__restrict __dest, const void *__restrict __src,
 __fortify_function void *
 __NTH (memset (void *__dest, int __ch, size_t __len))
 {
-  /* GCC-5.0 and newer implements these checks in the compiler, so we don't
-     need them here.  */
-#if !__GNUC_PREREQ (5,0)
-  if (__builtin_constant_p (__len) && __len == 0
-      && (!__builtin_constant_p (__ch) || __ch != 0))
-    {
-      __warn_memset_zero_len ();
-      return __dest;
-    }
-#endif
   return __builtin___memset_chk (__dest, __ch, __len, __bos0 (__dest));
 }
 
-- 
2.26.2

[COMMITTED 2.32] Remove __warndecl

[Siddhesh Poyarekar]

The macro is not used anymore, so remove it and warning-nop.c.

Reviewed-by: Florian Weimer <fweimer@redhat.com>

(cherry-picked from 34aec973e15a81926198f4b71ff99081dff87a92)
---
 debug/Makefile      |  2 +-
 debug/warning-nop.c | 70 ---------------------------------------------
 misc/sys/cdefs.h    |  3 --
 3 files changed, 1 insertion(+), 74 deletions(-)
 delete mode 100644 debug/warning-nop.c

diff --git a/debug/Makefile b/debug/Makefile
index 3a60d7af7a..0036edd187 100644
--- a/debug/Makefile
+++ b/debug/Makefile
@@ -51,7 +51,7 @@ routines  = backtrace backtracesyms backtracesymsfd noophooks \
 	    explicit_bzero_chk \
 	    stack_chk_fail fortify_fail \
 	    $(static-only-routines)
-static-only-routines := warning-nop stack_chk_fail_local
+static-only-routines := stack_chk_fail_local
 
 # Don't add stack_chk_fail_local.o to libc.a since __stack_chk_fail_local
 # is an alias of __stack_chk_fail in stack_chk_fail.o.
diff --git a/debug/warning-nop.c b/debug/warning-nop.c
deleted file mode 100644
index 4ab7e182b7..0000000000
--- a/debug/warning-nop.c
+++ /dev/null
@@ -1,70 +0,0 @@
-/* Dummy nop functions to elicit link-time warnings.
-   Copyright (C) 2005-2020 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 of the License, or (at your option) any later version.
-
-   In addition to the permissions in the GNU Lesser General Public
-   License, the Free Software Foundation gives you unlimited
-   permission to link the compiled version of this file with other
-   programs, and to distribute those programs without any restriction
-   coming from the use of this file. (The GNU Lesser General Public
-   License restrictions do apply in other respects; for example, they
-   cover modification of the file, and distribution when not linked
-   into another program.)
-
-   Note that people who make modified versions of this file are not
-   obligated to grant this special exception for their modified
-   versions; it is their choice whether to do so. The GNU Lesser
-   General Public License gives permission to release a modified
-   version without this exception; this exception also makes it
-   possible to release a modified version which carries forward this
-   exception.
-
-   The GNU C Library is distributed in the hope that it will be useful,
-   but WITHOUT ANY WARRANTY; without even the implied warranty of
-   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <sys/cdefs.h>
-
-static void
-__attribute__ ((used))
-nop (void)
-{
-}
-
-/* Don't insert any other #include's before this #undef!  */
-
-#undef __warndecl
-#define __warndecl(name, msg) \
-  extern void name (void) __attribute__ ((alias ("nop"))) attribute_hidden; \
-  link_warning (name, msg)
-
-#undef	__USE_FORTIFY_LEVEL
-#define __USE_FORTIFY_LEVEL 99
-
-/* Following here we need an #include for each public header file
-   that uses __warndecl.  */
-
-/* Define away to avoid warnings with compilers that do not have these
-   builtins.  */
-#define __builtin___memcpy_chk(dest, src, len, bos) NULL
-#define __builtin___memmove_chk(dest, src, len, bos) NULL
-#define __builtin___mempcpy_chk(dest, src, len, bos) NULL
-#define __builtin___memset_chk(dest, ch, len, bos) NULL
-#define __builtin___stpcpy_chk(dest, src, bos) NULL
-#define __builtin___strcat_chk(dest, src, bos) NULL
-#define __builtin___strcpy_chk(dest, src, bos) NULL
-#define __builtin___strncat_chk(dest, src, len, bos) NULL
-#define __builtin___strncpy_chk(dest, src, len, bos) NULL
-#define __builtin_object_size(bos, level) 0
-
-#include <string.h>
diff --git a/misc/sys/cdefs.h b/misc/sys/cdefs.h
index 19d9cc5cfe..38221d0b2a 100644
--- a/misc/sys/cdefs.h
+++ b/misc/sys/cdefs.h
@@ -124,13 +124,10 @@
 #define __bos0(ptr) __builtin_object_size (ptr, 0)
 
 #if __GNUC_PREREQ (4,3)
-# define __warndecl(name, msg) \
-  extern void name (void) __attribute__((__warning__ (msg)))
 # define __warnattr(msg) __attribute__((__warning__ (msg)))
 # define __errordecl(name, msg) \
   extern void name (void) __attribute__((__error__ (msg)))
 #else
-# define __warndecl(name, msg) extern void name (void)
 # define __warnattr(msg)
 # define __errordecl(name, msg) extern void name (void)
 #endif
-- 
2.26.2